Organic Fouling Behavior In Nanofiltration Membranes For The Removal of Per- and Polyfluoroalkyl Substances

Abstract

Per- and polyfluoroalkyl substances (PFAS) contamination in drinking water has increasingly become a focus of concern for health and environmental agencies around the globe. Increasing awareness of the detrimental health effects in organisms and humans as well at the bio-accumulative and persistent nature of these “forever chemicals” in the environment has reached drinking water regulations with many governing agencies enacting strict treatment regulations. These new and developing treatment regulations have spurred interest in the development and application of nanofiltration membranes as a possible treatment method for PFAS contamination in source waters. Nanofiltration has shown initial propensity as a viable and effective treatment method. The main concern in utilizing nanofiltration as a treatment method is the risk of membrane fouling. Fouling decreased the membrane flux, reducing the membrane efficiency and lifespan. In particular, fouling caused by natural organic matter (NOM) is a major concern when applying nanofiltration for PFAS removal. Not only does NOM cause severe fouling, it has the potential to affect specific interaction between PFAS, NOM, and the membrane itself by impacting membrane surface charge, hydrophilicity, functionality, and morphology. This study compared a commercially available NF270 nanofiltration membrane and a lab synthesized Covalent Organic Framework (COF) nanofiltration membrane with the purpose of analyzing the fouling behavior and mechanisms.